Accept null and 0 for microseconds argument in stream_select()

[zobo]

The previously merged change #6879 makes it impossible to write code that will run on pre PHP8.1 and post PHP8.1 without (at least) a deprecation warning.

Old implementation (https://github.com/php/php-src/blob/PHP-7.4.25/ext/standard/streamsfuncs.c#L764):
$tv_sec is NULL-able INT
$tv_usec is OPTIONAL INT (can't be null)

New implementation (https://github.com/php/php-src/pull/6879/files#diff-4294bfe38876196fc83b34d3b3a8d16919acbc8aaa68ce2fc77859f0ef46b787R757)
$tv_sec is NULL-able INT
$tv_usec is NULL-able INT

However the code also adds rules in case $tv_sec is NULL and $tv_usec is not NULL (https://github.com/php/php-src/pull/6879/files#diff-4294bfe38876196fc83b34d3b3a8d16919acbc8aaa68ce2fc77859f0ef46b787R792)

1. if it's 0 - a deprecation error emitted
2. if it's not 0 an exception is thrown

Here should be noted that the first argument $tv_sec acts as a gate-keeper to the php_select argument tv_p making the value of $tv_usec irrelevant in case $tv_sec is NULL.

While the second rule makes sense, as passing any number to $tv_usec effectively gets ignored and is logically incorrect, I have a problem with the first rule.

In pre PHP8.1 code if you passed both arguments to stream_select the the second HAD TO BE an integer.
Where in the current implementation - if we are talking the case where $tv_sec is NULL - it MUST NOT be, to avoid a deprecation warning.

Here is a great example of what I am talking about: https://github.com/sabre-io/event/pull/88/files

This Pull-Request proposes to allow (without warnings) $tv_usec to be 0 even if $tv_sec is NULL as this keeps the behavior of pre and post PHP8.1 the same.

[zobo]

Another argument could be:
If the current $tv_usec default value is 0 (see https://www.php.net/manual/en/function.stream-select.php) how come passing this value in 8.1 produces a deprecation warning...

[kelunik]

I'm fine with delaying the deprecation to a later point in the PHP 8 release line. You'll need to change the PR to target the 8.1 branch, as master is already 8.2.

[zobo]

Rebased onto 8.1. Thanks for considering this.